It has been known for a long time to use containers of a collapsible type, for example, for foodstuffs or expendable material such as sanitary articles and detergents. The contents can be both in liquid and in powder form.
By a container of a collapsible type is meant the type of container that consists of thin flexible walls which are joined in connecting portions to define a compartment. The volume of the compartment depends on the relative distance between the walls, which means that the volume depends on the filling ratio of the container.
This type of containers may have a number of different handle shapes, one of which is shown in WO 99/41155. This handle forms a hole pattern through which a user's hand can be inserted so that the container can be gripped and handled like a jug.
In SE 518,406, a corresponding container type has been further developed by gas-filled ducts being arranged in the connecting portion along at least one side of the container. The main purpose of this type of gas-filled duct is to increase the stability of the container, but also to make it more comfortable to grip. The gas-filled duct shown in this document is arranged to be filled in connection with the filling of the container with its contents. How this gas filling is done or how such equipment is designed has not been described.
Containers of a collapsible type are as a rule filled through a duct/opening which is defined by two opposite walls of the container. Such filling occurs with the container in an upright position, in which case the filling nozzle can act essentially in the vertical direction and be introduced into the duct between the two walls. This is a method that is well established and well functioning when supplying fluids in liquid form. The same method, however, causes great problems when supplying fluids in gaseous form due to difficulties in providing a gas-tight seal around the nozzle while the gas is being supplied. Additional problems arise when the gas-filled duct is to be sealed.
A solution to these problems is that the duct is filled with gas through a check valve integrated in the container. This technique is very expensive to apply to mass-produced containers, such as food containers where the duct is to be filled only once.
Therefore there is a need for a method and a device for gas filling of such ducts in collapsible containers, independently of the purpose of the gas-filled ducts. There is also a need for a further development of the construction of the duct to allow, in industrial use, easy filling with gas and also easy sealing. It will be appreciated that the duct intended for the purpose is not intended to be refilled.